The present invention concerns an apparatus for filling tubular casings with a pasty material, in particular gathered-together sausage cases with sausagemeat and a filling machine for producing sausages of pasty material, in particular sausagemeat.
Apparatuses for filling tubular casings are used, in particular, on filling machines for producing sausage strings, by means of which a pasty material like sausagemeat or the like is introduced portion-wise or in the form of portions of a predetermined amount into tubular casings of plastic or natural sausage skin. During the filling operation, the filled casing is divided off or twisted off at predetermined spacings between the individual filling steps, thereby producing sausage string portions which can be separated from each other, the portions being as far as possible of the same length and the same weight, which can then be separated from each other. The portions, which have been separated from each other, are then cut off to form the individual sausages, which inter alia are passed for further processing to a packaging machine.
Before the operation of filling the tubular casing, the tubular casing is drawn onto the filling tube of a filling device, in which case the tubular casing whose actual length corresponds to a multiple of the length of the filling tube is usually already concertinaed or gathered together so that the gathered casing, also referred as the gathered sausage case, is shorter than the filling tube. The gathered casings can be of different diameters, also referred to as calibers. The pasty material is pushed through the filling tube into the tubular casing, which is closed at one end, by means of a conveyor device, which is preferably connected upstream of the filling device, like for example a pump, in particular an adjustable vane pump or a conveyor screw. By virtue of the material introduced into the casing, the casing is gradually pulled off the open end of the filling tube. When a presettable amount or portion of the material has been introduced into the casing, the filling process is briefly interrupted and, in order to separate the introduced portion from the following portion, the casing portion which is disposed on the filling tube is rotated by means of the filling tube, which is mounted rotatably about its longitudinal axis. For that purpose, the filling tube is connected to a drive arranged on the receiving portion for carrying the filling tube. The filling tube is rotated about its longitudinal axis together with the gathered casing portion which has been pulled onto the filling tube and thus, after an amount of sausagemeat has been delivered into the tubular casing, this results in the production of a twist-off or constriction location. After the twisting-off operation has been effected, in which case the filling tube is rotated through a presettable angular amount, a predetermined amount of the material to be introduced is in turn pressed through the filling tube into the tubular casing and thus the casing is again pulled off the filling tube by a certain distance. After the material has been introduced, the twisting-off operation is started afresh and, with the continuous succession of the above-described process steps, this procedure results in a sausage string with individual string portions which can separated from each other.
To ensure that the sausage case is reliably also rotated on the filling tube, sausage case entrainment devices or sausage case braking units are provided, in particular at the open end of the filling tube, which press the casing onto the filling tube. In that respect, the sausage case braking unit has a rotatably mounted braking ring which is intended to afford a frictional or positively locking connection between the outer peripheral surface of the filling tube and a portion of the gathered sausage case which has been drawn there onto, and thus transmits the rotary movement produced by the filling tube to the casing portion which has been pulled thereover. At predetermined time intervals, the tubular casing which has been drawn onto the filling tube is used up and a fresh, gathered tubular casing has to be pulled onto the filling tube. For that purpose, the sausage case braking unit is to be moved away from the open end of the filling tube, by the sausage case braking unit being pulled away from the filling tube in the longitudinal direction thereof. A fresh, gathered tubular casing is pushed or pulled onto the filling tube from the open end thereof by means, for example, of a sausage case gripping device and then the sausage case entrainment device or sausage case braking unit is brought into contact again with the front open end of the filling tube, whereby the tubular casing is pressed onto the filling tube at least in the region of the tip thereof.
EP 2040556 B1 discloses a filling apparatus of the above-indicated general kind, having a filling tube onto which tubular casings are pulled or pushed at regular time intervals. To reduce the time intervals between the change operations and thus to improve the economy of the filling procedure, filling tubes are used which are of large lengthwise dimensions (minimum lengths) in order to be able to receive tubular casing portion of corresponding length. In that way, a predetermined minimum number of sausage string portions which are separated from each other can be produced, without changing the casing. From time to time, when pulling on the tubular casings comprising for example collagen or plastic material or when using natural sausage skins, or when the sausage case braking unit is again brought into contact with the casing, at the open end of the filling tube, the relatively long filling tube can suffer bending deformation. As a consequence of this, the bent filling tube can be caused to swing or oscillate during the operations of twisting off between the adjacent sausage string portions in the subsequent filling operation, and this can thus lead to the tubular casing being incorrectly loaded with pasty material. It can happen that the filling tubes are subjected to bending deformation in the casing change operation in such a way that in further operation of the filling apparatus the filling tubes can no longer be used and have to be replaced.